Conventional turbo-compressor apparatus, especially those designed to be used as turbosuperchargers for internal combustion engines, are generally constructed so as to have a compressor section, a turbine section and a bearing housing separating these sections. Lubricating oil is supplied to provide lubrication for a bearing in this housing in which a common shaft for the compressor impeller and turbine wheel rotates. The bearings in such a conventional turbo-compressor apparatus are generally fully floating sleeve type bearings which rotate at approximately half the rotational speed of the shaft. In U.S. Pat. No. 3,043,636 to MacInnes, however, a non-rotating sleeve bearing is used. This bearing, however, is a semi-floating device because a flange located at one end of the bearing is pinned to the bearing housing.
Turbo-compressors, according to these conventional designs, have an oil seal at each end of the bearing to prevent lubricating oil supplied to the bearing from entering the compressor section or the turbine section of the apparatus. The oil seal disposed near the turbine end of the bearing generally operates at relatively high temperatures and is a possible source of failure of the apparatus.
U.S. Pat. No. 2,911,138 to Birmann discloses a turbo-compressor in which a non-rotating shaft extends into a rotor assembly. Ball bearings rather than sleeve bearings are used in this design. Such bearings may present practical engineering difficulties if the apparatus is operated at a rotational speed close to its critical speed. Birmann attempts to solve this problem by providing means for mounting the stationary shaft and constraining it to move only substantially parallel to itself under stresses imparted to the shaft by the rotor. The shaft is supported by leaf spring members which converge towards the center of gravity of the rotor. Damping means in the form of elastic O-rings absorb vibrational energy imparted to the shaft.
Another design for a stationary shaft turbo-compressor type apparatus is disclosed in U.S. Pat. No. 3,692,436 to Connor et al.
While conventional turbo-compressors and various design modifications to these conventional devices have been relatively successful, they are generally comprised of a large number of machined components. These devices are in themselves expensive, costly to assemble and require substantial maintenance. Also, conventional stationary shaft designs do not themselves lend at all to down sizing due to the size restrictions and rotor speed (RPM) limitations imposed by ball type bearings.